1. Field of the Invention
This invention relates to a sheet winding apparatus, and more particularly to a sheet winding apparatus of the type having a stationary touch roller, which apparatus permits a sheet roll wound to a prescribed total amount to be moved from the winding position, cuts the trailing end of the sheet roll, wraps the cut end of the sheet around a new winding core set in the winding position, and starts winding the sheet on the new winding core.
2. Description of the Prior Art
Generally a sheet winding apparatus is used to produce sheet rolls by causing a given strip of sheet unwound from a master sheet roll or discharged from a production process or fabrication process to be wound in rolls of prescribed amounts on one winding shaft after another. The strip of sheet, when necessary, may be slit into a plurality of strips of a fixed width en route to the winding apparatus.
In the sheet winding apparatus, whenever the sheet has been wound up in a roll of prescribed amount, there must be performed the operations of cutting the trailing end of the sheet of the wound sheet roll, moving the finished sheet roll from the winding position to the sheet roll discharging position, setting a new winding core in place on a winding core support part of a winding mechanism, wrapping the cut leading end of the sheet around the new winding core, and moving the winding core to the winding starting position at which the winding core comes into contact with a touch roller.
As means of automatically performing all the operations mentioned above, a turret type winding apparatus has been developed and adopted for actual use (U.S. Pat. Nos. 3,734,423 and 3,784,122). This turret type winding apparatus has a plurality of positions for holding a winding core formed around the periphery of the turret type frame, so that the winding of the sheet will be effected continuously and automatically by allowing the work of removing a finished sheet roll to take place at one position and the work of setting a new winding core at another position while enabling sheet winding to continue at yet another position. This turret type winding apparatus permits continuous winding of the sheet and enjoys high operational efficiency. It nevertheless has a disadvantage in that it requires a complicated mechanism and requires a large space for installation and operation. Moreover, it inevitably requires a touch roller of a movable type for keeping the sheet against the winding core during the course of the sheet winding. The expression "movable type touch roller" as used in this specification means the type in which the winding shaft for supporting a winding core is fixed in place and, as the diameter of the roll gradually increases with the progress of the sheet winding, the touch roller is gradually moved away from th winding core, whereas the expression "stationary type touch roller" means the type in which the touch roller is supported on a fixed shaft and the winding shaft supporting thereon a winding core is disposed on the periphery of the touch roller and, as the diameter of the sheet roll grows with the progress of the sheet winding, the winding shaft is gradually moved away from the touch roller.
In the winding apparatus, the touch roller plays an important role in enabling the sheet to be accurately wound in a roll with prescribed tension. To be specific, the touch roller is rotated by being interlocked through the medium of a fine rotation speed adjusting mechanism with the rotary drive mechanism of the unwinding roller serving to advance the sheet toward the winding apparatus, so that the peripheral speed of the touch roller will be adjusted relative to the peripheral speed of the unwinding roller. Owing to this adjustment, the tension of the sheet on the verge of reaching the growing roll can be adjusted to the optimum level even when the tension of the sheet discharged from the unwinding roller happens to exceed or fall short of the optimum level. Since the sheet of properly adjusted tension is immediately wound on the winding core which is centrally driven with a prescribed amount of torque, the winding tension can be controlled with high precision, and the sheet can be wound under the optimum tension. The touch roller of this operating principle, therefore, proves particularly advantageous for the winding of a strip of sheet such as woven fabric whose wefts are liable to slide sideways while the fabric is being wound in a roll.
As described above, the touch roller is required to be interlocked with the unwinding roller and kept rotated with the rotational speed thereof finely adjusted at all times. In the case of the movable type touch rollers, however, since the touch roller is constantly in motion, it is difficult to transmit the finely adjusted rotational speed accurately to the touch roller and keep the touch roller in stable rotation.
For the purpose of accurate rotation of the touch roller, the touch roller of the stationary type proves advantageous over that of the movable type as described above. In the conventional sheet winding apparatus of the type using no turret type frame, since only one position is used for the attachment of the winding shaft, continuous, automatic sheet winding cannot be performed, and the operation of moving and discharging a finished sheet roll, that of setting a new winding core, and that of wrapping the cut leading end of sheet around the winding core have to be carried out manually.